Trunks are a type of men's swimwear style. They resemble shorts and cover from the waist to the mid-upper leg. Trunks are normally shorter than boardshorts, which extend to the knees. Trunks are the most popular type of male swimsuit in North America. They vary in style and design, though most are made of nylon with a mesh lining for quick drying.

A trunk is also a type of men's underwear similar to boxer briefs. Like boxer briefs, trunks cover the mid-section of the body (hence the name "trunk"). They are usually form-fitting like briefs, but some styles are loose fitting like boxer shorts. Trunk briefs extend over the legs like boxer shorts. Trunk briefs have a shorter inseam than regular boxer briefs, covering only the upper thighs and resting below the true waist.